Rotary saws such as circular saws, chop saws, radial arm saws, miter saws and table saws require that the operator properly align the material being cut with the saw blade. This takes time and care, but is critical for a proper cut.
There exist laser-based cut alignment devices which are externally mounted in the vicinity of the saw, and project a light beam along the cut line. These devices must be manually aligned before cutting begins, thus requiring experience and additional time. Also, the operator must monitor this additional piece of equipment in order to use the alignment device properly. Accordingly, devices of this nature are not practical for most saw owners and operators.